P0440 Code: The EVAP Code That Names Nothing

Short answer

The EVAP test failed; any second code says where

A P0440 code means the car decided something in the evaporative system was wrong without saying which part or which failure. It is the general heading that the specific evaporative codes sit under, which is why two shops can read it and name two different repairs.

OilAndMiles.com - A P0440 code, the error a prints as DTC P0440, is unusual among OBD-II codes: nearly every other one tells you something specific. A misfire names a cylinder, a leak code names a hole size, a valve code names a valve. This one names the system and stops, and that single fact explains most of what is frustrating about it.

What this page can pin down is who actually gets it, what owners found when they went looking, and which code beside it does the naming.

What does a P0440 code mean?

Something in the evaporative emission control system failed a check, and the code doesn't say what. The fuel in your tank gives off vapor. Rather than vent it to the air, the car stores it in a canister of charcoal and later draws it into the engine to be burned.

The computer tests that whole arrangement, and this code is what it stores when the test fails without a more specific result.

Chrysler writes the name out plainly in its own service documents. A 2023 bulletin for the Dodge Challenger lists four codes a technician might find together and translates each one: P0455 as a large leak, P0456 as a small leak, P0441 as purge system performance, and P0440 as a general EVAP system failure, using the trade's short name for the evaporative system.

Three of those four name a fault. The fourth names the system.

Worth knowing

A code that names nothing isn't a code that means nothing. It means the test ran, the system failed it, and the result didn't fall into one of the narrower buckets the car keeps a separate code for.

That's also why answers to this code contradict each other so freely. Someone whose P0440 turned out to be a cracked filler neck and someone whose P0440 was a vent valve are both telling the truth about their own car, and neither is telling you about yours.

Which cars actually report a P0440 code?

Mostly older GM and Stellantis vehicles, and two badges sit in the wrong place. Toyota draws 2,090 searches a month and is third in both places where somebody had to file a document. GM is the reverse: third in the searching, first in the complaint record.

We can show both gaps; we couldn't source a reason for either.

P0440 by corporate group: searches a month, owner complaints and manufacturer bulletins, each counted the same way across all three columns
Make	Searches a month	Complaints	Bulletins
Dodge, Jeep, Chrysler, Ram, Fiat and Alfa Romeo	2,570	12	53
Toyota, Lexus and Scion	2,090	6	7
Chevy, GMC, Pontiac, Buick and Cadillac	960	15	15

The complaint column counts 35 owner reports that name this code in any written form, across all model years, deduplicated so one report counts once however many parts it lists. The bulletin column counts 78 manufacturer filings that name it, with the maker of each one confirmed against NHTSA's own record rather than guessed from the shape of the document number.

The three groups hold 33 of the 35 complaints and 75 of the 78 bulletins; the other two complaints are a Nissan and a Subaru, and the other three bulletins come from other makers.

The age of the record matters more than the badge. 29 of the 35 complaints are on vehicles from the 2009 model year or earlier, and all 6 from the 2010 to 2025 model years, the window our other code pages count, are a Jeep, a Dodge or a Chrysler. This is largely a code from the first decade of , and the cars carrying it are old enough that rust and brittle plastic are ordinary findings rather than surprises.

The two models owners filed about most are the Chevy TrailBlazer, with five reports, and the Dodge Durango, with four, and the GMC Envoy follows with three. Single filings run from a 2002 Toyota Camry and a 2003 Dodge Ram 1500 to a 2017 Chrysler Pacifica, which is roughly the spread the searches show as well.

Why is Chrysler still writing about this code?

Because it keeps issuing fixes for this code on new models. General Motors filed 15 bulletins naming P0440 and every one is from 2000 to 2006, and Toyota filed seven in the same window.

Chrysler filed 53, and 52 of them are from 2016 or later.

The vehicles in those recent filings aren't old cars. They include the Dodge Challenger in 2019 and 2022, the Jeep Renegade in 2016 and 2018, the Alfa Romeo Giulia in 2017 and 2018, the Fiat 500X, and the Dodge Charger. Several of the documents are software updates rather than parts repairs, and several were revised more than once: one bulletin number runs through revision D.

Three rows of bars on one timeline from 2000 to 2023. General Motors and Toyota have bars only between 2000 and 2006 and nothing after. Chrysler has one bar in 2004, then a shaded empty stretch of nine years, then tall bars every year from 2016 to 2023 — Every archived bulletin naming P0440, placed on the year it was filed. The empty stretch is the point: two makers stopped and one didn't. Diagram: Oil & Miles

If you drive one of those, the useful question at the counter is whether anybody looked the code up against your build before ordering a part. A reprogram and a canister are very different invoices.

Chrysler vehicles also carry a part the others don't, the evaporative system integrity monitor switch, usually shortened to ESIM. It's the piece that tests whether the system holds pressure, and a 2015 Jeep Grand Cherokee owner filing this code had theirs replaced. Worth knowing the name before a quote uses it.

Does tightening the gas cap fix a P0440 code?

Sometimes, and the filed reports are mostly the times it didn't. 12 of the 35 complaints name the fuel cap. In seven of them the owner describes the cap being tightened or replaced and the code coming back.

What those owners found instead was further along the same path, or nothing at all:

A leak at the filler neck. A TrailBlazer owner replaced the cap, wrote that it wasn't the problem, and was later told the leak was at the filler neck.
A fuel filler pipe. A Corolla owner replaced the cap on a parts-store diagnosis, had the light and the fuel smell return, and replaced the filler pipe a week later.
A rollover valve. A Chrysler 300 owner with a strong fuel odor found a valve on top of the tank had popped off.
Nothing, twice. An Envoy XUV owner was sold one cap, had the light return, and was sold a second cap.

A straight run of pipe drawn left to right: a screw cap at the left end, then a stretch marked filler neck, then a longer stretch marked filler pipe, then a tank with a small round valve on top of it. Four numbered badges mark the cap, the neck, the pipe and the valve — The same run of pipe a leak can be anywhere on. The cap is first because it costs nothing to check, not because it's the likeliest. Diagram: Oil & Miles

What owners report

The cap is a reasonable first move because it costs almost nothing and it's occasionally right. What the filed reports show is how often it is treated as the answer rather than as the cheapest thing to rule out.

One of those reports was worth more than the rest. A Pathfinder owner smelling fuel near the filler area asked Nissan about a federal campaign, and the campaign was real: a recall of 372,250 vehicles over the fuel filler tube, not the cap. The panel below quotes it.

NHTSA complaint bulk download, file FLAT_CMPL, 35 complaints naming P0440, all model years.

Is P0440 the same as P0441 and P0446?

No, and the difference is the whole reason to read them. People search these three together because cars store them together. Every code in the family names something except this one:

P0441 is about flow. Vapor didn't move between the canister and the engine the way it was supposed to.
P0446 is about a valve. The vent valve was given an order and the car couldn't confirm it obeyed.
P0442 and P0456 are hole sizes. The system leaked, and the number says roughly how big.
P0440 is the heading. It can appear beside any of them, and on its own it narrows nothing.

A tank, a charcoal canister and an engine joined by arrows, with a purge valve on the line to the engine and a vent valve below the canister. Three numbered badges pin P0441 to the purge valve, P0446 to the vent valve and P0442 with P0456 to a brace spanning the tank and canister. A dashed rectangle labeled P0440 encloses all of it — Each specific code is a reading taken at one place. P0440 is the dashed line around everything, which is why it narrows nothing on its own. Diagram: Oil & Miles

In the complaint record P0442 and P0446 each turn up beside this code four times. If your scan gives you more than one code, the other one is the one to work from.

Will a P0440 code fail an emissions test?

Yes, and clearing it first makes things worse. In states that read the computer, a fails on its own. Erasing it doesn't produce a pass, it produces a car whose evaporative monitor reads not ready, and a station rejects an incomplete monitor the same way it rejects a code.

What sets your monitor back to ready is driving, not a scan tool, and the evaporative check is among the fussiest about the fuel level and temperature it waits for. 4 of the 35 complaints describe a car failing inspection over it: two emissions tests, a New Hampshire state inspection and a smog check.

What does it cost to fix a P0440 code?

Anywhere from a cap to a canister, and this code doesn't narrow it. That's not a dodge, it's the consequence of what the code is: the parts it can be in are every part the evaporative system is built from.

We priced that whole set at the counter across four vehicles on the P0455 page, and the codes that actually point at a part carry their own figures: P0442 for the small-leak end and P0446 for the vent valve. Reading one of those alongside your second code will get you closer to a real number than any figure attached to P0440 alone.

Three owners put a number in their federal filing, and the spread is the honest answer to what this code costs:

$475 on a 1999 Subaru Outback. A corroded fuel filler tube, $200 in parts and $275 in labor.
$900 quoted on a 2004 TrailBlazer EXT. A new cap first, which didn't fix it, then a significant leak found at the filler neck.
$2,200 on a 2003 TrailBlazer. The fuel inlet nozzle on the tank was leaking and the only repair was to replace the tank.

Those are what owners reported paying, not prices we researched, and the filings are from 2007, 2008 and 2009. They're worth reading for the shape rather than the figure: the same code, on two versions of the same vehicle, came to $900 and $2,200.

The 2003 car is also the argument for asking what gets tested. Its owner writes that the initial inspection found nothing, and that the leak only turned up when somebody ran a smoke test. A diagnosis that stops at a visual check can miss this fault entirely.

What should you do about a P0440 code?

All 4 steps below are free:

Write down every code, not just this one. P0440 on its own narrows nothing. P0440 beside P0456 is a small leak, beside P0441 is a flow problem, and that difference decides where anybody should be looking.
Check the cap properly, once. Take it off and look at the rubber seal inside it, the O-ring, for grit or splits. Refit it until it clicks, then pull it gently to see whether it moves in and out; a cap with play in it is not sealing. If the light returns after a few days of driving, the cap has been ruled out and buying a second one is repeating a test that already failed.
Ask whether a bulletin or a campaign covers your vehicle. Chrysler has filed dozens on this code since 2016, and one Nissan owner's fuel smell turned out to be a recall of 372,250 vehicles.
Ask what the shop intends to test before it quotes. A smoke test finds a leak, a meter finds a flow fault, and the two answer different questions. A quote that names a part before either has run is a guess with a price on it.

From the documents

What does the regulation call an evaporative system malfunction?

California's OBD-II rule is where the evaporative checks are written, and it defines the malfunction as exactly three conditions. Read them in order and it becomes obvious why this code is the odd one out: each of the three has its own more specific code, and none of them is P0440.

The second document is the one a Pathfinder owner pointed at, and it names a part the cap is often blamed for.

California Code of Regulations, Title 13, section 1968.2

The OBD II system shall detect an evaporative system malfunction when any of the following conditions exist13 CCR 1968.2 (e)(4.2.2)

The three conditions that follow are no purge flow, a leak at 0.040 inch, and a leak at 0.020 inch. Read at source from the published regulation.

NHTSA recall campaign 07V435000

Fuel leakage, in the presence of an ignition source, could result in a fireNissan North America, September 18, 2007

The cause was an under-coated fuel filler tube corroding through, and the remedy was to replace it. 372,250 Pathfinder and QX4 vehicles from 1997 to 2001, in 22 salt-belt states and the District of Columbia. Read at source from the federal recall record.

Conclusion

P0440 is where the answer starts, not where it ends

Every other code in the family points at a part. This one points at all of it, so the information worth having is never in the code itself. Here is where it is, and what the code costs you:

In the second code. P0441 is flow, P0446 is a valve, P0442 and P0456 are hole sizes. Any of them narrows the job; P0440 alone does not.
In one maker's filings, and only one. Chrysler filed 53 bulletins naming this code and 52 are from 2016 or later. General Motors filed 15 and Toyota 7, and both stopped by 2006.
Further down the pipe than the cap. 12 of the 35 filed complaints name the fuel cap, and in 7 the cap was tightened or replaced and the code came back. What they found was the filler neck, the filler pipe, or a valve on the tank.
In the age of the car, more than the badge. 29 of the 35 complaints are on vehicles from 2009 or earlier.
It fails an , and clearing it first is worse. The monitor then reads not ready, which a station rejects the same way as a code.
The filed bills run $475 to $2,200. Two versions of the same vehicle, same code, $900 and $2,200.

So the first free move is to write down every code, not just this one. Oil & Miles reads the regulation and the manufacturers' filings rather than the forum consensus, and every part this system is built from is priced at the counter on the P0455 page.

Common questions

Asked most often

What does the P0440 code mean?

It means the evaporative system failed a check without saying which part or which kind of failure. Chrysler's own service documents call it a general EVAP system failure, in a list where the three codes beside it name a large leak, a small leak and a purge flow problem. European cars, under EOBD, use the same code.

Can I drive with code P0440?

Usually, as far as driveability goes. 4 of the 35 complaints describe the engine stalling or trying to. Seven use the words safety hazard or fire, and that's about leaking fuel, not the engine. If you can smell fuel, treat that as the urgent part rather than the lamp.

What is the most common cause of a P0440 code?

There's no single one. A shop usually looks at the cap, the purge valve and the charcoal canister first, because those are cheapest to test. Owners' reports turned up the filler neck, the filler pipe, a rollover valve, the canister and its valves, the tank and the cap, and the cap was most often replaced without fixing it.

Will a P0440 code clear itself?

The lamp can, after several drives where the evaporative check runs and passes. The fault doesn't. If the cause was a cap left loose once, the light going out is real. If the light returns, the check has found the same thing again.

Is P0440 a Toyota problem?

Less than the searching suggests. Toyota, Lexus and Scion draw about 2,090 searches a month on this code, but Toyota filed 7 of the 78 manufacturer bulletins naming it and owners filed 6 of the 35 complaints, and every Toyota bulletin dates from 2000 to 2006. The Stellantis brands filed 53 bulletins, 52 of them from 2016 or later.

How do I fix a P0440 code on a Toyota?

The same way as on any car, by reading the second code first. Toyota's own filings on this code all date from 2000 to 2006, so on a newer Toyota there's no maker document pointing at a known fault, and the diagnosis has to come from the system rather than the badge.

Is P0440 the same as P0442?

No. P0442 is a leak of a stated size, about 0.040 inch under the California rule. P0440 is the heading above it and names no size at all. The two turn up together in the complaint record four times.

Does a P0440 code mean my gas cap is bad?

Not by itself. Check it once, because it's free. 12 of the 35 complaints name the cap, and in seven the owner describes it being tightened or replaced and the code returning, and what they found afterwards was further down the fuel filler path.

What people ask next

Sources

California Code of Regulations, Title 13, section 1968.2, read at source: (e)(4.2.2) for the three conditions that define an evaporative system malfunction. California Air Resources Board, read September 21, 2026
NHTSA recall campaign 07V435000, September 18, 2007, Nissan Pathfinder and Infiniti QX4 from 1997 to 2001, for the fuel filler tube coating, the 22 states named and the 372,250 vehicles. NHTSA, read September 21, 2026
NHTSA manufacturer communications archive, swept in full, for the 78 bulletins naming P0440 and the maker behind each one. NHTSA, read September 21, 2026
Chrysler bulletin 1809523, August 29, 2023, 2022 Dodge Challenger, for the powertrain module flash and its own wording for the four evaporative codes. Chrysler (FCA US, LLC), read September 21, 2026
NHTSA complaint bulk download, file FLAT_CMPL, counted by complaint number, for the 35 complaints naming this code across all model years and what owners replaced. NHTSA, file dated August 25, 2026

How this was compiled

The search figures are our own keyword export for this code, 1,000 queries summed by make rather than by head term, because a make that appears in dozens of phrasings is easy to miss if only the biggest one is counted.

The complaint count treats one owner report as one complaint. The federal file writes a separate row for each component a report names, so counting rows inflates it: 53 rows here are 35 reports. Three reports carry an extra row that isn't the car, a 1969 Dodge, a trailer maker and a blank record, and each is counted under the car it actually describes.

The code counts in every form owners write it, PO440 with a letter O included. Unlike our other code pages this one counts every model year, because the code belongs to older cars; the 2010 to 2025 window those pages use holds 6 of the 35.

What we didn't do

We didn't price the parts again on this page. They're the same parts the whole evaporative system is built from, priced across four vehicles for P0455, and a census repeated under a second code number isn't a second census. The three dollar figures above are a different thing: what owners said they paid, quoted from their own filings.

We didn't quote the GM bulletin an Envoy owner named in their complaint. The number is in their filing and the document is older than the archive we hold, so we couldn't read it ourselves, and we don't republish a document we haven't opened.

We didn't explain why Toyota owners search this code more than the record suggests they should, 2,090 a month against seven bulletins and six complaints. We can show the gap; we couldn't source a reason for it.

We didn't answer it for a BMW. About 190 searches a month pair this code with that badge, and we found no BMW in the 35 complaints and no BMW bulletin among the 78, so we have nothing to tell a BMW owner that we wouldn't be making up. The sections above are the general answer, and the second code is still the thing to read.

We didn't open a car. Everything above is the regulation, the manufacturers' own filings and the federal complaint record.

The three figures on this page are what owners told NHTSA they paid, in complaints filed in 2007, 2008 and 2009, and they aren't prices we researched or checked. Prices we did research are on the pages the cost section links to, compiled in August and September 2026 for the US market. This article is general information, not advice about your specific vehicle, see the disclaimer.